The use of suppositories to deliver beta-lactam antibiotics which are orally inactive is known. Such suppositories are ordinarily composed of the antibiotic, a base substance such as WITEPSOLS, e.g. WITEPSOL H-15, which are a mixture of higher chain (C.sub.12 -C.sub.18) fatty acid glycerides, and a substance to promote absorption of the antibiotic in the rectum. Such substances, such as, probenacid and fatty acids of C.sub.8 to C.sub.14 chain length have been used in the past to promote absorbability of antibiotics in suppository form. See, for example, Japanese Application No. 20590 - J5-2105-220 and U.S. Pat. No. 4,38,306 respectively. Furthermore, the use of mixtures of fatty acid glycerides of C.sub.2 -C.sub.12 chain length as enhancers has also been disclosed, see, for example, Swiss Application No. 858/84.